668685397 has 4 divisors (see below), whose sum is σ = 669679660. Its totient is φ = 667691136.

The previous prime is 668685383. The next prime is 668685401. The reversal of 668685397 is 793586866.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 102292996 + 566392401 = 10114^2 + 23799^2 .

It is a cyclic number.

It is not a de Polignac number, because 668685397 - 2¹⁵ = 668652629 is a prime.

It is a super-2 number, since 2×668685397² = 894280320322095218, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668685307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 496122 + ... + 497467.

It is an arithmetic number, because the mean of its divisors is an integer number (167419915).

Almost surely, 2^668685397 is an apocalyptic number.

It is an amenable number.

668685397 is a deficient number, since it is larger than the sum of its proper divisors (994263).

668685397 is an equidigital number, since it uses as much as digits as its factorization.

668685397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 994262.

The product of its digits is 13063680, while the sum is 58.

The square root of 668685397 is about 25858.9519702559. The cubic root of 668685397 is about 874.4613379024.

The spelling of 668685397 in words is "six hundred sixty-eight million, six hundred eighty-five thousand, three hundred ninety-seven".